小程序js控制图片属性隐藏

 <view class='back'>
    <image class='img' src="{{back}}"></image>
</view> 

  data: {
    back: "/img/back.gif",
  },

  getCars: function (e) {
    var that = this;
    //查询绑定车辆数据
    wx.request({
      url: app.globalData.root + "car.do",
      data: {
        "openid": e
      },
      method: 'GET',
      header: {
        'Content-type': 'application/json'
      },
      success: function (res) {
        that.setData({
          carList: res.data,
        })
        if (res.data.length > 0) {
          that.setData({
            back: ""
          })
        }
      }
    });
  }